Radiant heater for preventing frost damage to plant life



Sept. 19, 1950 A.'W. FARRALL 2,522,935

RADIANT HEATER FOR PREVENTING FROST DAMAGE TO PLANT LIFE Filed Nov. 20,1947 2 Sheets-Sheet l INVENTOR. ArThur W. Farrell.

ATTORNEY Sept. 19, 1950 A. W.'FARRALL RADIANT HEATER FOR PREVENTINGFROST DAMAGE TO PLANT LIFE 2 Sheets-Sheet 2 Filed Nov. 20, 1947INVENTOR. Ar'rhur w. Farrell.-

BY Mf ATTORNEY Patented Sept. 19, 1950 UNITED STATES PATENT OFFICERADIANT HEATER FOR PREVENTING FROST DAMAGE TO PLANT LIFE ApplicationNovember 20, 1947, Serial No. 787,174

6 Claims.

This invention relates to apparatus for preventing the formation offrost by means of radiant heat.

The present invention constitutes an improvement on the inventiondisclosed in my copending application for Letters Patent Serial No.715,512, filed December 11, 1946.

The principal object of the present invention is to provide a highlyefficient radiant type heater of relatively great heating capacity.

Another object of the invention is to provide a heater of the radianttype constructed in such a manner that a relatively large percentage ofheat therefrom is directed toward the perimeter of the plot to beprotected from frost.

A still further object of the invention is to provide a heater havingreflecting means thereon which is adjustable to distribute the heat tobest advantage within the area to be protected from frost.

These objects and others ancillary thereto will more fully appear in thefollowing description, when read in connection with the accompanyingdrawings, wherein:

Figure 1 is an elevational view partially in section of a heaterembodying the present invention;

Figure 2 is a plan view of the same, parts being broken away to moreclearly disclose the construction thereof;

Figure 3 is an elevational view partly in section of another form ofheater embodying the present invention;

Figure 4 is a plan view thereof; and

Figure 5 is a fragmentary cross-sectional view taken on substantiallythe line 5-5 of Figure 4.

Referring now more particularly to the drawings, and especially toFigures 1 and 2 thereof, the invention is shown as embodied in a radianttype heater comprising generally a tubular heat exchanger it having aburner l I mounted at the lower end thereof, a reflector l2 andsupporting means i3.

The tubular heat exchanger comprises a side wall having a lower portionI4 of generally frusto-conical form converging downwardly. The side wallalso has an upper frusto-conical section I5 converging upwardly. The twoportions it and 55 may be made in one piece or separately, as desired.If made in two pieces the larger ends, or bases, of the two portions arepreferably welded together about their entire peripheries. At the upperend of the upper portion it of the side wall is a stack 16. The stack isneed not be particularly high, for it is pro-- ill " supporting frame22.

vided more for supporting the reflector I2, as will be more fullypointed out hereinafter, than it is for carrying away the products ofcombustion. Mounted inside of the stack 16 are two cross pieces 51 and18, preferably at right angles to each other and in spaced apartrelation, which support a rod I9 at the lower end of which is a baflie20.

At the lower end of the heat exchanger I0 is a bottom plate 22 having acentral opening therein. The bottom plate 2| is rigidly connected to thelower portion E4 of the side wall. A suitable supporting frame 22 issuspended from the plate 2!. The burner H is mounted upon the The burnerH may be of any suitable character that will provide the necessary heatunits.

Preferably the parts of the heat exchanger just described, namely, theside wall, stack and bottom plate, are formed from aluminized" sheetsteel. Sheets of steel are covered with a thin coating of aluminum whichis melted and flowed on the steel sheets. The coating of aluminumresists oxidation of the steel, permitting the heat exchanger to beheated to temperatures higher than usual, thus increasing the output ofradiant heat.

The reflector is a relatively large annular plate, preferably formedfrom polished aluminum. The reflector '2 has a central opening whichreceives the stack [6. Preferably the diameter of the opening in theplate 12 is slightly larger than the diameter of the stack to preventdirect contact between the stack and reflector. The reflector will notthen be damaged by the hot stack. The inner perimeter of the reflectoris supported by brackets l-oa attached to the stack. As has beenmentioned previously, the plate I2 is quite large and is relativel thinand flexible. In order to support the reflector H2 at its outerperimeter, four links 23 are provided. These links are connected bymeans of brackets 24 at uniformly spaced points about the outerperiphery of the reflector l2. The links 23 are connected at their innerends to eyes 25 mounted on a collar 26 secured to the upper end of thestack IS.

The reflector I2 is preferably in the form of a relatively flat frustumof a cone. In the particular form of the invention shown in Figures 1and 2 the conical surface of the reflector is inclined at an angle ofapproximately 5 to the horizontal. This angle may be varied, if desired,by providing adjusting means in the of turnbuckles 2'? in the links 23.By taking up or loosening the turnbuckles 21 the shape of the cone maybe varied. The particular inclination of the reflector depends upon thedistance that it is desired to direct the heat rays from the heater. Itmay be desired to incline the reflector outwardly and upwardly incertain instances.

The heater shown may be supported upon any suitable framework. It isdesirable that the heater be raised a substantial distance above thesurface of the ground. The supports shown comprise three legs 28removably mounted in sockets within brackets 29. The brackets 29 arerigidly attached to the bottom plate 2| of the heater. The lower ends ofthe legs 23 can be forced into the ground and, if desired, thepossibility of the heater being accidentally overturned may be preventedby plates 30 which are pegged to the ground by means of wooden or metalpegs 3| extending through the plates. The plates are provided with holestherein which receive the lower ends of the legs 28.

The heater is utilized to protect the plants within a predetermined areaby being located centrally thereof. Whenthe burner H is operated, heatis radiated from the side wall of the heat exchanger. Most of the heatradiates outwardly from the heat exchanger in a direction perpendicularto the side wall thereof. Thus, the heat rays emanating from the lowerportion M are distributed outwardly along the broken lines extendingtherefrom inFigure 1. The heat rays from the upper portion |5 areradiated upwardly and outwardly toward the reflector I2 by which theyare reflected outwardly and downwardly. By means of the direct heat raysfrom the lower portion l4 and the reflected rays from the upper portion,the bulk of the heat radiated from the heat exchanger will be directedout toward the perimeter of the plot which it is desired to protect. Itis this portion of the plot which is the most difiicult to furnishprotection to, and

'by means of the particular shape of the heater disclosed thatprotection is afforded. The part of the plot closely adjacent to theheater will be heated by means of radiant heat from the bottom of theheat exchanger, from the burner itself, and from stray heat rays fromthe side walls. The form of the invention shown in Figures 3 to 5embodies that feature of the previous modification wherein the bulk ofthe heat rays are directed from the heat exchanger itself outwardly andupwardly and are then turned downwardly and outwardly by means ofreflectors. In this form of the invention there are a plurality offrusto-conical sections all converging upwardly to a plurality ofreflectors.

In the form of the invention shown in these figures a heat exchanger 55is provided with a tubular side wall comprising six frusto-conicalsections 5|, 52, 53, 54, 55 and 56. All of these sections convergeupwardly. The upper ends of the sections 5| to 54 are joined to thelower ends of the respective sections thereabove by means of annularrings 57. The outer peripheries of the rings 51 are welded to the lowerends of the sections immediately thereabove. The inner peripheach lowerbaflie is smaller than the one next above it.

The side wall of the heat exchanger is mounted upon a bottom plate 60having a central opening therein which receives a burner 6|. The bottomwall 60 is supported upon a suitable framework. In the form of theinvention shown, the framework comprises four downwardly extending tubes62 rigidly connected to the bottom plate. The tubes 62 receiveupstanding legs 63 connected to a sled-like frame 64, the character ofwhich is clearly evident in the drawings. Preferably the legs 62 haveuniformly spaced openings 65 therein which receive pins- 66 that supportthe lower ends of the tube' 62. By varying the positions of the pins 66in the different holes 65 the height of the burner above the ground canbe adjusted.

The burner 6| is supported on a suitable framework 61' connected to thetube 62.

Thin aluminum reflectors 68 are connected to the side walls of theheater adjacent the lower ends of eachof the sections 52 to 56. Theformation of the reflectors and the manner of attachment to the sidewall of the heat exchanger is shown in detail in Figure 5. The innerperiphery of each reflector 68 is provided with a bead 69. The beadrests upon a rod 10 bent into circular form and welded to an outturnedflange H at the lower end of each of the sections 52 to The flange 7|and rod 10 hold the reflector away from the extremely hot surface of thead- ,spaced points, by a U-shaped yoke 14. The yoke "Mmay-be bolted tothe reflector by bolts 15. On

each yoke 74 a small ring 16 is attached. The side of the ring isprovided with a tapped opening receiving aset screw 11. The rings 15receive four uprights 18 which are firmly attached to a supportingframework of the heater by means of struts .19 and 80.

The reflectors 68 are preferably in the form of shallow frustums ofcones. The inclination of the conical surfaces may be adjusted byloosening the set screws 11 and sliding the rings 18- up or down to thedesired position where they are again clamped by the set screws.

In the form of the invention shown in Figures 3 we most of the heatradiated from the side wall of the heater is directed outwardly andupwardly from the sections 5| to 55. When the radiant heat rays strikethe reflectors E8 the rays are directed outwardly and downwardly towardthe plot to be protected. Some heat is radiated to the ground directlyfrom the annular rings 51, from the bottom plate '60, and from theburner itself. These rays will suffice to protect the area closelyadjacent to the burner while the reflected rays are distributed outtoward the periphery of the plot.

In both forms of the invention the flames from the burner are deflectedoutwardly against the side walls of the heat exchanger by the battles 20and 59. Thus, the heat produced in the burner is efficiently utilized toprovide radiant heat.

It will be noted that in both forms of the invention reliance forprotection of the perimeter of the plot is placed principally upon therays emanating from the upwardly converging sections of the burner sidewall which are reflected 1 by the reflectors l2 and 68. It has beenfound that heaters of this character are particularly efficient inforcing the heat out toward the perimeter of the plot where it isparticularly desired.

It has been found that heaters of this type are capable of protectingquite large areas from frost. The heat supplied in the form of radiantheat rays to the outer portions of the plot is quite uniformlydistributed. Both types of heaters have protected relatively tenderplant life against any damage due to frost to a distance of 120 feetfrom the heater when the temperature an inch above the ground reached26.4.

Thus, it will be seen that the present invention provides an extremelyefiicient radiant type heater. It is relatively simple to manufacture.

The scope of the invention is indicated in the appended claims.

I claim:

1. Combustion apparatus for heating by means of infra-red rays anunenclosed area many times the horizontal extent of said combustionapparatus comprising a heat exchanger having a tubular side wall, saidside wall comprising a first frusto-conical portion tapering inwardlyand downwardly and a second frusto-conical portion adjoining the upperextremity of said first portion and tapering inwardly and upwardlytherefrom, and a relatively wide annular reflector plate mounted abovethe second frustoconical portion and substantially transverse to theaxis thereof, the reflector plate and the second frusto-conical portionbeing arranged at such a relative angle to each other that substantiallyall rays normal to the conical portion strike said plate and arereflected and directed outwardly beyond the outer confines of any areabeneath said plate.

2. Combustion apparatus for heating by means of infrared rays anunenclosed area many times the horizontal extent of said combustionapparatus comprising a heat exchanger having a tubular side wall, saidside wall comprising two frusto-conical portions having vertical axesand with their bases joined together, and a relatively wide annularreflector plate above the upper frusto-conical portion and connected atits inner periphery to said side wall, said refiector plate extendingsubstantially transverse to the axis of said tubular side wall and beingarranged at such a relative angle to the upper irusto-conical portionthat substantially all rays normal to the conical portion strike saidplate and are reflected and directed outwardly beyond the outer confinesof any area beneath said plate.

3. Combustion apparatus for heating by means of infrared rays anunenclosed area many times the horizontal extent of said combustionapparatus comprising a heat exchanger having a tubular side wall, saidside wall having a portion thereof tapering upwardly and inwardly, and arelatively wide annular reflector plate mounted above said taperedportion and substantially transverse to the axis thereof, the reflectorplate and the tapered portion being arranged at such a relative angle toeach other that substantially all rays normal to the conical portionstrike said plate and are reflected and directed outwardly beyond theouter confines of any area beneath said plate.

4. Combustion apparatus as defined in claim 3 wherein means areconnected to said heat exchanger and the outer perimeter of saidreflector plate for partially supporting the latter.

5. Combustion apparatus as defined in claim 3 wherein means areconnected to said heat exchanger and the outer perimeter of saidreflector plate for partially supporting the latter, said means beingadjustable whereby to regulate the position of the reflector platerelative to the heat exchanger.

6. Combustion apparatus as defined in claim 3 wherein said side wall isformed from sheets of ferrous metal coated with aluminum.

ARTHUR W. FARRALL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,553,922 Aram Sept. 15, 19251,658,690 Sanctuary et al. Feb. 7, 1928 1,680,005 Bevier Aug. 7, 19281,749,710 Maddalena Mar. 4, 1930 1,767,670 Huff June 24, 1930 2,133,649Abbot Oct. 18, 1938

